The present invention relates to an interior part of vehicle such as a vehicle seat and a manufacturing method of the interior part.
Regarding a vehicle seat such as an automobile seat, various functions such as safety, holding property, sitting comfort, and vibration absorption performance are required. At the same time, as the seat is a large part among the interior parts of automobile, various requirements regarding outer appearance and design property are made of the seat. Especially, a trim cover of the vehicle seat significantly influences the design property of the vehicle seat.
The trim cover of the vehicle seat is manufactured by combining plural cloths (trim cover pieces) forming the trim cover and sewing them. Japanese Published Unexamined Patent Application No. Hei 8-266764 discloses this type of technique.
According to Japanese Published Unexamined Patent Application No. Hei 8-266764, plural clothes forming the trim cover, used in a seatback of a vehicle seat, are joined three-dimensionally, so as to be fitted to the outer contour of a foam-made cushion body covered with the trim cover.
Further, according to this publication, in joining of terminals of the plural cloths when the terminal of one cloth to be joined to another cloth is cut in an arc projecting curve while the end of the other cloth to be joined with the end of the former cloth is cut in a straight line, an operator feeds the both ends in a sewing machine while aligning them.
Further, according to this publication, a stretch sewing material (cloth) having a terminal in a projecting or recess curve, to be joined with another terminal, is expanded or contracted on a jig such that the terminal is fixed in a straight line, then the other sewing material (cloth) is overlaid on the former sewing material, and they are integrally sewn and joined with the sewing machine.
The trim cover is often quilting-stitched from the light of design and sitting comfort. For example, a trim cover used in a seatback or seat cushion of a vehicle seat is manufactured by an operator's feeding both of plural quilting-stitched clothes i.e. pieces of the trim cover into a sewing machine while manually aligning them, thus sewing up the ends of the pieces.
However, upon this sewing up, a stitch pattern on one piece is often shifted from that on the other cloth. That is, the sewing up of plural cloths is performed while the opposite sides to the stitch patterns (the sides where the stitch patterns are unshown) are faced up. Accordingly, it is extremely difficult for even a skilled sewing-machine operator to perform sewing up while accurately align the stitch patterns. Especially in the case of thick quilting material, the degree of difficulty in sewing is high and variation in the sewing result occurs by product. Thus the design property is impaired.